/* ----------------------------------------------------------------------
* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
*
* $Date:        19. March 2015
* $Revision: 	V.1.4.5
*
* Project: 	    CMSIS DSP Library
* Title:	    arm_cfft_radix2_q15.c
*
* Description:	Radix-2 Decimation in Frequency CFFT & CIFFT Fixed point processing function
*
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*   - Redistributions of source code must retain the above copyright
*     notice, this list of conditions and the following disclaimer.
*   - Redistributions in binary form must reproduce the above copyright
*     notice, this list of conditions and the following disclaimer in
*     the documentation and/or other materials provided with the
*     distribution.
*   - Neither the name of ARM LIMITED nor the names of its contributors
*     may be used to endorse or promote products derived from this
*     software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
* -------------------------------------------------------------------- */

#include "arm_math.h"

void arm_radix2_butterfly_q15(
    q15_t *pSrc,
    uint32_t fftLen,
    q15_t *pCoef,
    uint16_t twidCoefModifier);

void arm_radix2_butterfly_inverse_q15(
    q15_t *pSrc,
    uint32_t fftLen,
    q15_t *pCoef,
    uint16_t twidCoefModifier);

void arm_bitreversal_q15(
    q15_t *pSrc,
    uint32_t fftLen,
    uint16_t bitRevFactor,
    uint16_t *pBitRevTab);

/**
 * @ingroup groupTransforms
 */

/**
 * @addtogroup ComplexFFT
 * @{
 */

/**
 * @details
 * @brief Processing function for the fixed-point CFFT/CIFFT.
 * @deprecated Do not use this function.  It has been superseded by \ref arm_cfft_q15 and will be removed
 * @param[in]      *S    points to an instance of the fixed-point CFFT/CIFFT structure.
 * @param[in, out] *pSrc points to the complex data buffer of size <code>2*fftLen</code>. Processing occurs in-place.
 * @return none.
 */

void arm_cfft_radix2_q15(
    const arm_cfft_radix2_instance_q15 *S,
    q15_t *pSrc)
{

    if(S->ifftFlag == 1u)
    {
        arm_radix2_butterfly_inverse_q15(pSrc, S->fftLen,
                                         S->pTwiddle, S->twidCoefModifier);
    }
    else
    {
        arm_radix2_butterfly_q15(pSrc, S->fftLen,
                                 S->pTwiddle, S->twidCoefModifier);
    }

    arm_bitreversal_q15(pSrc, S->fftLen, S->bitRevFactor, S->pBitRevTable);
}

/**
 * @} end of ComplexFFT group
 */

void arm_radix2_butterfly_q15(
    q15_t *pSrc,
    uint32_t fftLen,
    q15_t *pCoef,
    uint16_t twidCoefModifier)
{
#ifndef ARM_MATH_CM0_FAMILY

    unsigned i, j, k, l;
    unsigned n1, n2, ia;
    q15_t in;
    q31_t T, S, R;
    q31_t coeff, out1, out2;

    //N = fftLen;
    n2 = fftLen;

    n1 = n2;
    n2 = n2 >> 1;
    ia = 0;

    // loop for groups
    for (i = 0; i < n2; i++)
    {
        coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));

        ia = ia + twidCoefModifier;

        l = i + n2;

        T = _SIMD32_OFFSET(pSrc + (2 * i));
        in = ((int16_t) (T & 0xFFFF)) >> 1;
        T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF);

        S = _SIMD32_OFFSET(pSrc + (2 * l));
        in = ((int16_t) (S & 0xFFFF)) >> 1;
        S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF);

        R = __QSUB16(T, S);

        _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);

#ifndef ARM_MATH_BIG_ENDIAN

        out1 = __SMUAD(coeff, R) >> 16;
        out2 = __SMUSDX(coeff, R);

#else

        out1 = __SMUSDX(R, coeff) >> 16u;
        out2 = __SMUAD(coeff, R);

#endif //     #ifndef ARM_MATH_BIG_ENDIAN

        _SIMD32_OFFSET(pSrc + (2u * l)) =
            (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);

        coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));

        ia = ia + twidCoefModifier;

        // loop for butterfly
        i++;
        l++;

        T = _SIMD32_OFFSET(pSrc + (2 * i));
        in = ((int16_t) (T & 0xFFFF)) >> 1;
        T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF);

        S = _SIMD32_OFFSET(pSrc + (2 * l));
        in = ((int16_t) (S & 0xFFFF)) >> 1;
        S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF);

        R = __QSUB16(T, S);

        _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);

#ifndef ARM_MATH_BIG_ENDIAN

        out1 = __SMUAD(coeff, R) >> 16;
        out2 = __SMUSDX(coeff, R);

#else

        out1 = __SMUSDX(R, coeff) >> 16u;
        out2 = __SMUAD(coeff, R);

#endif //     #ifndef ARM_MATH_BIG_ENDIAN

        _SIMD32_OFFSET(pSrc + (2u * l)) =
            (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);

    }                             // groups loop end

    twidCoefModifier = twidCoefModifier << 1u;

    // loop for stage
    for (k = fftLen / 2; k > 2; k = k >> 1)
    {
        n1 = n2;
        n2 = n2 >> 1;
        ia = 0;

        // loop for groups
        for (j = 0; j < n2; j++)
        {
            coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));

            ia = ia + twidCoefModifier;

            // loop for butterfly
            for (i = j; i < fftLen; i += n1)
            {
                l = i + n2;

                T = _SIMD32_OFFSET(pSrc + (2 * i));

                S = _SIMD32_OFFSET(pSrc + (2 * l));

                R = __QSUB16(T, S);

                _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);

#ifndef ARM_MATH_BIG_ENDIAN

                out1 = __SMUAD(coeff, R) >> 16;
                out2 = __SMUSDX(coeff, R);

#else

                out1 = __SMUSDX(R, coeff) >> 16u;
                out2 = __SMUAD(coeff, R);

#endif //     #ifndef ARM_MATH_BIG_ENDIAN

                _SIMD32_OFFSET(pSrc + (2u * l)) =
                    (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);

                i += n1;

                l = i + n2;

                T = _SIMD32_OFFSET(pSrc + (2 * i));

                S = _SIMD32_OFFSET(pSrc + (2 * l));

                R = __QSUB16(T, S);

                _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);

#ifndef ARM_MATH_BIG_ENDIAN

                out1 = __SMUAD(coeff, R) >> 16;
                out2 = __SMUSDX(coeff, R);

#else

                out1 = __SMUSDX(R, coeff) >> 16u;
                out2 = __SMUAD(coeff, R);

#endif //     #ifndef ARM_MATH_BIG_ENDIAN

                _SIMD32_OFFSET(pSrc + (2u * l)) =
                    (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);

            }                         // butterfly loop end

        }                           // groups loop end

        twidCoefModifier = twidCoefModifier << 1u;
    }                             // stages loop end

    n1 = n2;
    n2 = n2 >> 1;
    ia = 0;

    coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));

    ia = ia + twidCoefModifier;

    // loop for butterfly
    for (i = 0; i < fftLen; i += n1)
    {
        l = i + n2;

        T = _SIMD32_OFFSET(pSrc + (2 * i));

        S = _SIMD32_OFFSET(pSrc + (2 * l));

        R = __QSUB16(T, S);

        _SIMD32_OFFSET(pSrc + (2 * i)) = __QADD16(T, S);

        _SIMD32_OFFSET(pSrc + (2u * l)) = R;

        i += n1;
        l = i + n2;

        T = _SIMD32_OFFSET(pSrc + (2 * i));

        S = _SIMD32_OFFSET(pSrc + (2 * l));

        R = __QSUB16(T, S);

        _SIMD32_OFFSET(pSrc + (2 * i)) = __QADD16(T, S);

        _SIMD32_OFFSET(pSrc + (2u * l)) = R;

    }                             // groups loop end


#else

    unsigned i, j, k, l;
    unsigned n1, n2, ia;
    q15_t xt, yt, cosVal, sinVal;


    //N = fftLen;
    n2 = fftLen;

    n1 = n2;
    n2 = n2 >> 1;
    ia = 0;

    // loop for groups
    for (j = 0; j < n2; j++)
    {
        cosVal = pCoef[ia * 2];
        sinVal = pCoef[(ia * 2) + 1];
        ia = ia + twidCoefModifier;

        // loop for butterfly
        for (i = j; i < fftLen; i += n1)
        {
            l = i + n2;
            xt = (pSrc[2 * i] >> 1u) - (pSrc[2 * l] >> 1u);
            pSrc[2 * i] = ((pSrc[2 * i] >> 1u) + (pSrc[2 * l] >> 1u)) >> 1u;

            yt = (pSrc[2 * i + 1] >> 1u) - (pSrc[2 * l + 1] >> 1u);
            pSrc[2 * i + 1] =
                ((pSrc[2 * l + 1] >> 1u) + (pSrc[2 * i + 1] >> 1u)) >> 1u;

            pSrc[2u * l] = (((int16_t) (((q31_t) xt * cosVal) >> 16)) +
                            ((int16_t) (((q31_t) yt * sinVal) >> 16)));

            pSrc[2u * l + 1u] = (((int16_t) (((q31_t) yt * cosVal) >> 16)) -
                                 ((int16_t) (((q31_t) xt * sinVal) >> 16)));

        }                           // butterfly loop end

    }                             // groups loop end

    twidCoefModifier = twidCoefModifier << 1u;

    // loop for stage
    for (k = fftLen / 2; k > 2; k = k >> 1)
    {
        n1 = n2;
        n2 = n2 >> 1;
        ia = 0;

        // loop for groups
        for (j = 0; j < n2; j++)
        {
            cosVal = pCoef[ia * 2];
            sinVal = pCoef[(ia * 2) + 1];
            ia = ia + twidCoefModifier;

            // loop for butterfly
            for (i = j; i < fftLen; i += n1)
            {
                l = i + n2;
                xt = pSrc[2 * i] - pSrc[2 * l];
                pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1u;

                yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
                pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1u;

                pSrc[2u * l] = (((int16_t) (((q31_t) xt * cosVal) >> 16)) +
                                ((int16_t) (((q31_t) yt * sinVal) >> 16)));

                pSrc[2u * l + 1u] = (((int16_t) (((q31_t) yt * cosVal) >> 16)) -
                                     ((int16_t) (((q31_t) xt * sinVal) >> 16)));

            }                         // butterfly loop end

        }                           // groups loop end

        twidCoefModifier = twidCoefModifier << 1u;
    }                             // stages loop end

    n1 = n2;
    n2 = n2 >> 1;
    ia = 0;

    // loop for groups
    for (j = 0; j < n2; j++)
    {
        cosVal = pCoef[ia * 2];
        sinVal = pCoef[(ia * 2) + 1];

        ia = ia + twidCoefModifier;

        // loop for butterfly
        for (i = j; i < fftLen; i += n1)
        {
            l = i + n2;
            xt = pSrc[2 * i] - pSrc[2 * l];
            pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);

            yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
            pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);

            pSrc[2u * l] = xt;

            pSrc[2u * l + 1u] = yt;

        }                           // butterfly loop end

    }                             // groups loop end

    twidCoefModifier = twidCoefModifier << 1u;

#endif //             #ifndef ARM_MATH_CM0_FAMILY

}


void arm_radix2_butterfly_inverse_q15(
    q15_t *pSrc,
    uint32_t fftLen,
    q15_t *pCoef,
    uint16_t twidCoefModifier)
{
#ifndef ARM_MATH_CM0_FAMILY

    unsigned i, j, k, l;
    unsigned n1, n2, ia;
    q15_t in;
    q31_t T, S, R;
    q31_t coeff, out1, out2;

    //N = fftLen;
    n2 = fftLen;

    n1 = n2;
    n2 = n2 >> 1;
    ia = 0;

    // loop for groups
    for (i = 0; i < n2; i++)
    {
        coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));

        ia = ia + twidCoefModifier;

        l = i + n2;

        T = _SIMD32_OFFSET(pSrc + (2 * i));
        in = ((int16_t) (T & 0xFFFF)) >> 1;
        T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF);

        S = _SIMD32_OFFSET(pSrc + (2 * l));
        in = ((int16_t) (S & 0xFFFF)) >> 1;
        S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF);

        R = __QSUB16(T, S);

        _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);

#ifndef ARM_MATH_BIG_ENDIAN

        out1 = __SMUSD(coeff, R) >> 16;
        out2 = __SMUADX(coeff, R);
#else

        out1 = __SMUADX(R, coeff) >> 16u;
        out2 = __SMUSD(__QSUB(0, coeff), R);

#endif //     #ifndef ARM_MATH_BIG_ENDIAN

        _SIMD32_OFFSET(pSrc + (2u * l)) =
            (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);

        coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));

        ia = ia + twidCoefModifier;

        // loop for butterfly
        i++;
        l++;

        T = _SIMD32_OFFSET(pSrc + (2 * i));
        in = ((int16_t) (T & 0xFFFF)) >> 1;
        T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF);

        S = _SIMD32_OFFSET(pSrc + (2 * l));
        in = ((int16_t) (S & 0xFFFF)) >> 1;
        S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF);

        R = __QSUB16(T, S);

        _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);

#ifndef ARM_MATH_BIG_ENDIAN

        out1 = __SMUSD(coeff, R) >> 16;
        out2 = __SMUADX(coeff, R);
#else

        out1 = __SMUADX(R, coeff) >> 16u;
        out2 = __SMUSD(__QSUB(0, coeff), R);

#endif //     #ifndef ARM_MATH_BIG_ENDIAN

        _SIMD32_OFFSET(pSrc + (2u * l)) =
            (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);

    }                             // groups loop end

    twidCoefModifier = twidCoefModifier << 1u;

    // loop for stage
    for (k = fftLen / 2; k > 2; k = k >> 1)
    {
        n1 = n2;
        n2 = n2 >> 1;
        ia = 0;

        // loop for groups
        for (j = 0; j < n2; j++)
        {
            coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));

            ia = ia + twidCoefModifier;

            // loop for butterfly
            for (i = j; i < fftLen; i += n1)
            {
                l = i + n2;

                T = _SIMD32_OFFSET(pSrc + (2 * i));

                S = _SIMD32_OFFSET(pSrc + (2 * l));

                R = __QSUB16(T, S);

                _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);

#ifndef ARM_MATH_BIG_ENDIAN

                out1 = __SMUSD(coeff, R) >> 16;
                out2 = __SMUADX(coeff, R);

#else

                out1 = __SMUADX(R, coeff) >> 16u;
                out2 = __SMUSD(__QSUB(0, coeff), R);

#endif //     #ifndef ARM_MATH_BIG_ENDIAN

                _SIMD32_OFFSET(pSrc + (2u * l)) =
                    (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);

                i += n1;

                l = i + n2;

                T = _SIMD32_OFFSET(pSrc + (2 * i));

                S = _SIMD32_OFFSET(pSrc + (2 * l));

                R = __QSUB16(T, S);

                _SIMD32_OFFSET(pSrc + (2 * i)) = __SHADD16(T, S);

#ifndef ARM_MATH_BIG_ENDIAN

                out1 = __SMUSD(coeff, R) >> 16;
                out2 = __SMUADX(coeff, R);
#else

                out1 = __SMUADX(R, coeff) >> 16u;
                out2 = __SMUSD(__QSUB(0, coeff), R);

#endif //     #ifndef ARM_MATH_BIG_ENDIAN

                _SIMD32_OFFSET(pSrc + (2u * l)) =
                    (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);

            }                         // butterfly loop end

        }                           // groups loop end

        twidCoefModifier = twidCoefModifier << 1u;
    }                             // stages loop end

    n1 = n2;
    n2 = n2 >> 1;
    ia = 0;

    // loop for groups
    for (j = 0; j < n2; j++)
    {
        coeff = _SIMD32_OFFSET(pCoef + (ia * 2u));

        ia = ia + twidCoefModifier;

        // loop for butterfly
        for (i = j; i < fftLen; i += n1)
        {
            l = i + n2;

            T = _SIMD32_OFFSET(pSrc + (2 * i));

            S = _SIMD32_OFFSET(pSrc + (2 * l));

            R = __QSUB16(T, S);

            _SIMD32_OFFSET(pSrc + (2 * i)) = __QADD16(T, S);

            _SIMD32_OFFSET(pSrc + (2u * l)) = R;

        }                           // butterfly loop end

    }                             // groups loop end

    twidCoefModifier = twidCoefModifier << 1u;

#else


    unsigned i, j, k, l;
    unsigned n1, n2, ia;
    q15_t xt, yt, cosVal, sinVal;

    //N = fftLen;
    n2 = fftLen;

    n1 = n2;
    n2 = n2 >> 1;
    ia = 0;

    // loop for groups
    for (j = 0; j < n2; j++)
    {
        cosVal = pCoef[ia * 2];
        sinVal = pCoef[(ia * 2) + 1];
        ia = ia + twidCoefModifier;

        // loop for butterfly
        for (i = j; i < fftLen; i += n1)
        {
            l = i + n2;
            xt = (pSrc[2 * i] >> 1u) - (pSrc[2 * l] >> 1u);
            pSrc[2 * i] = ((pSrc[2 * i] >> 1u) + (pSrc[2 * l] >> 1u)) >> 1u;

            yt = (pSrc[2 * i + 1] >> 1u) - (pSrc[2 * l + 1] >> 1u);
            pSrc[2 * i + 1] =
                ((pSrc[2 * l + 1] >> 1u) + (pSrc[2 * i + 1] >> 1u)) >> 1u;

            pSrc[2u * l] = (((int16_t) (((q31_t) xt * cosVal) >> 16)) -
                            ((int16_t) (((q31_t) yt * sinVal) >> 16)));

            pSrc[2u * l + 1u] = (((int16_t) (((q31_t) yt * cosVal) >> 16)) +
                                 ((int16_t) (((q31_t) xt * sinVal) >> 16)));

        }                           // butterfly loop end

    }                             // groups loop end

    twidCoefModifier = twidCoefModifier << 1u;

    // loop for stage
    for (k = fftLen / 2; k > 2; k = k >> 1)
    {
        n1 = n2;
        n2 = n2 >> 1;
        ia = 0;

        // loop for groups
        for (j = 0; j < n2; j++)
        {
            cosVal = pCoef[ia * 2];
            sinVal = pCoef[(ia * 2) + 1];
            ia = ia + twidCoefModifier;

            // loop for butterfly
            for (i = j; i < fftLen; i += n1)
            {
                l = i + n2;
                xt = pSrc[2 * i] - pSrc[2 * l];
                pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1u;

                yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
                pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1u;

                pSrc[2u * l] = (((int16_t) (((q31_t) xt * cosVal) >> 16)) -
                                ((int16_t) (((q31_t) yt * sinVal) >> 16)));

                pSrc[2u * l + 1u] = (((int16_t) (((q31_t) yt * cosVal) >> 16)) +
                                     ((int16_t) (((q31_t) xt * sinVal) >> 16)));

            }                         // butterfly loop end

        }                           // groups loop end

        twidCoefModifier = twidCoefModifier << 1u;
    }                             // stages loop end

    n1 = n2;
    n2 = n2 >> 1;
    ia = 0;

    cosVal = pCoef[ia * 2];
    sinVal = pCoef[(ia * 2) + 1];

    ia = ia + twidCoefModifier;

    // loop for butterfly
    for (i = 0; i < fftLen; i += n1)
    {
        l = i + n2;
        xt = pSrc[2 * i] - pSrc[2 * l];
        pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);

        yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
        pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);

        pSrc[2u * l] = xt;

        pSrc[2u * l + 1u] = yt;

    }                             // groups loop end


#endif //             #ifndef ARM_MATH_CM0_FAMILY

}
